Tungsten titanium carbide, wtic



Patented v UNITED STATES PATENT OFFICE 2,113,353 TUNGSTEN TITANIUMCARBIDE, WTiOz Philip M. McKenna, Unity Township, Westmoreland County,Pa.

No Drawing. Application December 13, 1937,

Serial No. 179,551

7 Claims. (01. 23-44) This invention relates to carbides, and more theamount and proportions of the tungsten and particularly to a newcomposition of matter comtitanium content, the excess of tungsten ortiposed of tungsten, titanium and carbon, and cortanium remaininguncombined, so as to be readily responding to the chemical formulaWTiCz. separable therefrom, along with the other result- The principalobject of the invention is the proing substances.

duction of a carbide containing tungsten and The new carbide substanceis prepared by heattitanium which will be extremely hard and 01' ingtungsten, or a substance containing tungsten great value and utility asa material for use, in such as tungsten oxide, or alloys of tungsten,accordance with the usual principles of powder with titanium, or asubstance containing titani- 10 metallurgy, in the production of hardcompoum, such as titanium oxide, in the presence of 10 sitions ofmatter, in order to effect great hardcarbon, in a menstruum metal, forwhich purpose ness combined with great strength, together with nickelhas been found to be preferable, the suba low thermal conductivity andother characterstance being then separated by chemical and istics, whichwill enable the hard compositions of mechanical means from the resultingmass. I matter made from such carbide material to have have, likewise,prepared such carbide substance, 15

great utility and durability when used as the repeatedly, by employingas a menstruum metal cutting points in the cutting of metal athighcobalt, or a mixture of cobalt and nickel, and speeds, when used asdies, and when used to proit is probable that menstruum metals otherthan vide corrosion-resisting surfaces, and for other nickel and cobaltmay be used. However, be-

similar uses. cause of the lowcost and the ease of its re- 20 A furtherobject of the invention is the promoval, Iconsider the use of nickel tobe preferduction of such a carbide, containing tungsten, able from acommercial 'standpointi 'The amount which, when used in the productionof hard comof menstruum metal or metals, may vary widely, positions ofmatter, in accordance with the usual from an effective amount up to anamount conprinciples of powdermetallurgy, and with a siderably inexcessof'the tungsten content, and 2 binder material containing powderedtungsten or I have found that the usef'of nickel or cobalt inmolybdenum, or carburized tungsten or molybdean amount approximatelyequal-to the amount num, or other compounds of tungsten or molyb oftungsten gives the best results-froma comdenum, with or without nickelor cobalt, will yield mercial standpoint. If only a small amount of noneof its carbon content to any of the metals mn truum al s 11S d.- t must"func i n y 30 so used as a binder in such hard compositions of solutionof a little of the tungstenandftitanium matter. I at a time, suchdissolved metals apparently com- A still further object of the inventionis to bining in solution toform the carbide, thus freeprovide such acarbide which, when used as an ing the mens ruum m t l so h it i availale ingredient in such a hard composition of matter, to dissolve afurther quantity f the n n renders it possible to include in suchhard-comand titanium. As will be apparent, the time position of matter ahigher percentage of menecessary to complete thereaction under suchtallic tungsten as a binder than has been praccircumstances is undulyprolonged. ticable heretofore, whereby the toughness and AS stat d abert e p s pp i a i n s d 40 breaking strength of such composition ofmatter rected t0 the new composition of matter which is 40 can beincreased without a material decrease of produced by a process hereindisclosed, butwhich the hardness and cutting ability of suchcompoprocess is described in detail, and claimed, in my sition ofmatter. copending application, Serial No. 179,552, filed of Furtherobjects of the invention, together with even date herewith, to whichreference is hereby -15 details of the steps by which the invention isput made. into practice, will be apparent from the follow- I havelikewise invented certain new and useful ing specification. improvementsin hard compositions of matter The new carbide substance which I haveincontaining this new carbide substance as an invented, and obtained bythe process herein degredient, described and claimed in my copending 5scribed, is apparently a double carbide of tungapplication, Serial No.179,553, filed of even date sten and titanium corresponding to thechemical herewith, and a process for making such hard formula WTiCz, andcontaining substantially compositions of matter, described and claimedin 71.9% W, 18.7% Ti, and 9.4% C, and it has been my copendingapplication, Serial No. 179,554, also invariably obtained by followingthe process herefiled of even date herewith, to both of which apindescribed, regardless of wide variations in plications reference ishereby made.

In carrying out the process of forming this new carbide substance, thetungsten, titanium and menstruum metal ingredients, are heated,preferably in a graphite crucible, for a period of about five hours, ata temperature above 1600 C., and preferably approximately 2100 C. I haveused slugs of tungsten metal, with bars of commercial nickel meltingstock, with titanium oxide, and graphite chips, all placed together in agraphite crucible. I have also incorporated the tungsten in the form ofWO: in such melts, with equally good results.

I have found it advisable to mix with the other materials chips orturnings of graphite, in an amount constituting about 5% of the tungstenand titanium materials combined. The mass resulting from the heatingprocess, after cooling, is crushed, treated with water solutions ofhydrochloric acid and a small amount of nitric acid, at boilingtemperatures, or with similar oxidizing acid solutions such ashydrochloric acid to which potassium perchlorate has been added, treatedwith ammonia or other hydroxide solutions to remove W03, again treatedwith aqua regia, or other oxidizing acid solutions, to dissolve the Ni,and again treated with hydroxide solutions to dissolve any remainingW03. At various stages, during such treatments, the powdered material issubjected to mechanical concentration, as by panning or gravityconcentration, as on a Wilfley table, to remove loose graphite andparticles of light impurities. The particles remaining after suchchemical and mechanical separation of other compounds, are greyparticles having a metallic lustre. These particles are further treated,preferably in platinum dishes, with strong solutions of hydrofluoricacid, at a temperature up to its boiling point, to dissolve suboxides orblue oxides of tungsten, such as W02, and any other impurities. Thehydrofluoric acid solution is removed by repeated washing anddecantation, and the remaining particles are carefully panned orotherwise concentrated, as by gravity methods and dried, the remainingparticles being grey in color, with high metallic lustre, havingsurfaces which are predominantly conchoidal and of a size averaginggreater than .01 mm. in largest cross-section dimensions.

As a specific example of the process followed in the formation of suchnew carbide substance, and the characteristics, as shown by test, of theproduct obtained thereby, the following procedure was followed in oneinstance.

There was placed in a crucible, 6" in diameter, of substantially puregraphite:

Grams Tungsten rods 1840 Powdered TiO 800 Ni melting stock 2800 Thegraphite crucible, with such contentstherein, was placed in an electricinduction furnace and heated, during a period of approximately an hour,to a temperature of 2100 C., and maintained at such temperature for aperiod of eight hours. After cooling, the product of such heatingprocess was removed by breaking away the graphite crucible, and the masswas crushed by hammer and by a jaw crusher, together with coarse ballmilling, until the particles thereof would pass a 40-mesh screen. Theparticles were repeatedly treated with water mixtures of hydrochloricacid to which a small amount of nitric acid had been added, the acidmixture being repeatedly boiled. After such acid treatments, the

particles were treated with ammonia solutions, to remove any W03, andwere again treated with aqua regia, to dissolve nickel and nickel alloysand other impurities, and finally were again treated withammoniasolutions. At various stages during such acid and hydroxide treatments,the particles were subjected 'to mechanical concentration by panning andwere also concentrated by gravity methods on a Wilfley table to removeloose graphite and other light impurities, leaving only grey particles,obviously having a metallic lustre. The particles were further treated,in platinum dishes, with strong solutions of hydrofluoric acid, at atemperature up to the boiling point, to dissolve suboxides of tungstensuch as W02. The hydrofluoric acid solution was removed by washing withwater, and repeated decantation with fresh water and the particles wereagain carefully "panned and concentrated by gravity methods. From theabove-mentioned mixture of materials, 1030 grams of such particles wereobtained.

A carbon analysis was made of samples from such particles, and showed acarbon content of 9.40% C, which is quite close to the carbon content of9.39% C, which theoretically should be present according to the formulaWTiCz. This discrepancy of the carbon content found is within the errorof analysis of the carbon content of materials of this type. A test ofthe tungsten and titanium content of such particles showed that theycontained 71.86% W and 18.75% Ti, corresponding exactly with the contentthat theoretically would be present in WTiCz. Such particles were foundto have a specific gravity of 9.72, which is much lower than would beindicated theoretically for a mixture of WC and TiC in the proportionsof the metallic contents found by tests. Inasmuch as the specificgravity of WC is 15.64 and that of TiC is 5.0055, the calculatedspecific gravity, on the assumption that this product is a mixture of WCand TiC, would be 10.29. The melting point of the product was found tobe higher than that of WC (2867i- 50 C.) and may be higher than that ofTiC (3146: 50 C.). If the substance were a solid solution of TiC in WC,that is, a eutectic, one would expect the melting point to be lower thanthat of WC. Particles of the new carbide substance were treated with astandardized solution of hydrofluoric acid containing one drop of nitricacid and were found to dissolve in two hours, whereas an equivalentamount of a mixture of WC and TiC was dissolved in the same solution inless than two minutes.

In order to test further the new carbide substance WTlCz, as comparedwith a mixture of WC and TiC having the same ultimate metallic content,pairs of test pieces of hard compositions of matter were formed, asdescribed in my copending application Serial No. 179,554, and using thesame amount of the same binding materials, and following exactly thesame process, except that one contained WTlCz and the other contained anequivalent amount of a mixture of WC and TiC. A number of such pairs oftest pieces were made, using different binding materials, and withdifferent proportions of carbide material and of binding material. Inevery case the hard compositions containing the new carbide substanceWTiCz were found to exhibit a characteristically lower thermalconductivity than those made with mixtures of WC and TiC, showed greaterstrength and hardness, and likewise showed on repeated tests, in whichsuch new hard anaasa compositions of matter were used as a me cuttingtool point in machining steels and copper-silicon cast iron, muchgreater resistance to cratering and resistance to erosion and wear fromchips oi both steel and cast iron, the compositions containing WTIC:lasting from four to five times as long as did the compofltionscontaining mixtures of WC and TIC, when used under identical conditionsin the same machine, and cutting the same material at the same rate ofspeed.

The new carbide substance has been manufactured on a commercial basis inlarge quantities, and has been unvarylng in its physical characteristicsand in its chemical analysis, being always produced in the expectedquantity, as particles of a rather uniform size, with high metalliclustre, and with the surfaces of the particles predominantly conchoidalas seen under a highpower microscope.

I believe that the hard carbide substance, made by the processdescribed, is a new chemical compound corresponding chemically to theformula WTiCz. My reasons for such belief are (1) the unvaryingcomposition of the substance produced as described and alwayscorresponding to the formula WTiC: by analysis, even when the quantitiesof the ingredients of the mixture initially heated are widely varied toinclude a large excess of W or of Ti; (2) its chemically difl'erentbehavior when treated with aqua regia, as compared with WC and 110, aswell as its chemically difl'erent behavior when treated withhydrofluoric acid containing a small amount of nitric acid; (3) itsproducing, when formed into a hard composition of matter in a binder ofnickel or cobalt or other binder material, a composition which lastsfrom four to five times as long as a similar hard composition of mattermade in identically the same way but with a mixture of WC and TIC, andhaving the same ultimate chemical analysis; (4) the characteristicallylower thermal conductivity of hard compositions of matter containing it;(5) its lower density, as compared with that of a mixture of WC and TiChaving the same vention is directed to such new composition of I mattereither in its pure form, as produced by the process described, or withsuch incidental impurities.

What I claim is:

1. The new chemical compound corresponding I to the formula W'IiCz.

2. The new chemical compound consisting of tungsten, titanium and carboncombined in the proportion of one atom of tungsten, one atom of titaniumand two atoms of carbon.

3. A carbide compound containing 71.86 per cent W, 18.75 per cent Ti and9.39 per cent C.

4. A chemical compound containing approximately 71.9 per cent tungsten,approximately 18.7 per cent Ti, and approximately 9.4 per cent C., thatis unattacked by aqua regia.

5. A chemical compound containing approximately 71.9 per cent W.,approximately 18.7 per cent '11, and approximately 9.4 per cent C., inthe form of particles averaging greater than .01 mm. in largestcross-section dimension and having a high metallic lustre.

6. A chemical compound containing approximately 71.9 per cent W.,approximately 18.7 per cent Ti, and approximately 9.4 per cent C., andhaving a specific gravity of approximately 9.72.

7. A chemical compound containing approximately 71.9 per cent W.,approximately 18.7 per cent Ti, and approximately 9.4 per cent 0., inthe form of particles having surfaces predominantly conchoidal.

PHILIP M. McKENNA.

